The removal of sulphur compounds from fossil hydrocarbon (HC) streams, such as Natural Gas Condensate, Kerosene, Jet Fuel, Diesel and Fuel Oil, down to ultra low ppm levels is of major technical importance in industry and society due to the fact that sulphur containing compounds can have negative effects on technical operations and the environment. For instance, the presence of chemically-combined sulphur, such as organosulphur compounds, in hydrocarbon streams can cause corrosion of processing equipment and engine parts. Further, the emission of SOx and NOx (oxides of nitrogen and sulphur) from the combustion of fossil fuels containing sulphur and nitrogen, causes damage to the environment. Of particular concern is the presence of Poly Nuclear Aromatics (PAH) Sulphur, which when combusted, can produce toxic and probable carcinogenic compounds in the environment.
With increasing emphasis on eliminating or minimizing sulphur discharge to the atmosphere, attention has turned to the removal of sulphur and nitrogen compounds from hydrocarbon feedstocks before said hydrocarbons are combusted. Feedstock desulphurization is mandated in most countries of the world. Legislation in the United States currently limits the sulphur level in fuels such as gasoline and diesel hydrocarbon to 30 ppm and 15 ppm respectively. This limit of 15 ppm is more stringent in other parts of the world, such as the EU, where allowable sulphur levels are as low as ≤10 ppm. This is also the mandatory level adopted by other countries as well, such as Japan, Australia and New Zealand.